Most known pump dispensers used in dispensing personal and household care products discharge contents from their pump chambers the down stroke after the user has depressed an actuator. Discharge does not occur and the pump chambers are refilled during the subsequent return stroke.
in certain applications, however, it is desirable for the pump dispenser to spray continuously during both down strokes and return strokes as long as it is repeatedly actuated by the user.
Two types of continuous spray dispensers are known in the art. The first type is disclosed in U.S. Pat. Nos. 4,503,996 and 4,646,969. In this type of dispenser, a piston divides a pump chamber into a relatively large lower chamber and a smaller upper chamber. The piston is constructed to exhibit a predetermined leak during its down stroke so that while the lower chamber is emptied of fluid during discharge, a portion of the fluid in the lower chamber is deliberately leaked into the smaller upper chamber. During the return stroke, the upper chamber is emptied of fluid during discharge and the lower chamber is refilled with fluid. The discharges from this type of dispenser are unbalanced, since the volume dispensed during the return stroke must be smaller than that dispensed on the down stroke. Moreover, this type of dispenser utilizes a ball type check valve which relies at least partially on gravity for its operation, so that the dispenser can only be operated properly in upright position.
The second type of dispenser is disclosed in U.S. Pat. No. 5,092,495. In this second type of dispenser, a piston divides a pump chamber into a relatively large lower chamber and a smaller upper chamber in the same manner as described above. The leaky type of piston shown in the first type of dispenser is replaced in the second type of dispenser by a free running piston which during the downstroke allows free passage of liquid from the lower chamber into the upper chamber. The discharges from this second type of dispenser are also unbalanced, since the volume dispensed during the return stroke is smaller than that dispensed on the down stroke. Moreover, this second type of dispenser also utilizes the ball type check valve and the dispenser can only be operated properly in upright position.
The present invention is directed toward a new type of continuous spray pump dispenser which not only overcomes the disadvantages of the prior art dispensers described above but also has additional advantages which will be explained below.